SEMI C3 - Specification for Gases

This Standard was technically approved by the Gases Global Technical Committee. This edition was approved for publication by the global Audits and Reviews Subcommittee on February 2, 2017. Available at www.semiviews.org and www.semi.org in March 2017; originally published in 1981; previously published April 2013.

Recognizing the importance of impurity content of gases in the manufacture of semiconductors, suppliers responded by introducing products with improved analytical characterization, notably for trace impurities.

The SEMI Gases Committee began its efforts in the spring of 1979. With this publication, the committee establishes the definitions, general procedures, specifications, and analytical procedures for the gases listed in the index.

Products which meet all of the requirements may be described as ‘meeting SEMI Specifications.’

Where an analytical procedure different from that provided is substituted by a supplier or user, the burden of proof is on said supplier or user to confirm the equivalency. It should be noted that the following list of criteria was considered when determining the specified analytical method.

•Reliability

•Ease of Use

•Maintenance

•Precision

•Accuracy

•Sensitivity

•Versatility

•Availability of Equipment

The specifications provided by this Standard are intended to serve for gases to be used in the manufacture and processing of semiconductors and advanced electronic devices and circuits. The specifications and the associated test procedures are guidelines based on the experience of suppliers and users. The function of the specifications is to establish desired standards of quality.

Where feasible, a specification of content shall be expressed as a numerical limit in units of mole per mole (mole/mole). For a major component, the value (assay or purity) shall be expressed as a minimum permissible limit. For an impurity, the value shall be expressed as a maximum permissible limit. A gas conforming to the specifications will commonly contain more of the major component than the minimum permissible limit or contain less of an impurity (or several impurities) than the SEMI C3 maximum permissible limit. In neither case shall the gas be considered as of higher quality than that defined by the specification.

It is not practical to consider every impurity or contaminant that might be present. For certain applications, it is recognized that more stringent or additional specifications and procedures might be required. The intent of these specifications and the associated procedures is, on one hand, to assure that a gas is suitable for the common uses to which it may be put in the manufacture and processing of semiconductor devices and, on the other hand, to be consistent with contemporary manufacturing processes for that gas.

The committee is continuing work on improvement of specifications and procedures, and addition of other gases and systems such as mixed gases. The committee welcomes comments, suggestions, and recommendations.